Ironically, there was a real-life Andy Gump who had surgery. This was Andy Wheat, born in 1890 in Bay St, Louis, Mississippi. He had an infected tooth that led to the removal of his entire lower jaw. After cartoonist Sidney Smith met Wheat through his brother, Dr. Thomas Smith, a dentist in Bloomington, Illinois, he decided to use Wheat as the basis for a comic strip character. Wheat was 27 when The Gumps debuted in newspapers in 1917. Later, he legally changed his name to Andy Gump. Note that he is dressed like Andy Gump in the photo below.

The word "gump" was introduced by James Russell Lowell in The Biglow Papers (1848).